For a case that very bright and dark portions exist simultaneously, a solid-state image sensor having a wide dynamic range is required to facilitate an excellent imaging. Conventionally, as recited in patent literature (PTL) 1, an image sensor that has two MOS transistors in which a current amplification factor of one MOS transistor is increased to ten times higher than the current amplification factor of the other MOS transistor is proposed.
In the device of the PTL 1, signal charges that are accumulated in an accumulation region via the one MOS transistor have a sensitivity that is ten times higher than signal charges accumulated in an accumulation region via the other MOS transistor. Thus, it is possible to increase the dynamic range. However, in recent application fields such as in-vehicle cameras, monitoring cameras and the like, an image sensor of high sensitivity is required which has a high-speed response that facilitate imaging of a fast-moving target, and has a much wider dynamic range.